Rotary or angularly displaceable bolt forks of the aforedescribed type are commonly used in vehicle door locks and generally are mounted on or in a housing which can be provided with the aforementioned notch or slot and mounted upon an edge of the door which is swung into the closed position to thereby enable a stationary pin on the doorpost to enter the mouth of the fork and, as the door-closing motion continues, the angularly disposed bolt into its latching position in which the pawl is rendered effective to prevent angular displacement of the pivotal bolt in the opposite sense tending to release the pin.
Of course, an actuating mechanism is provided to allow release of the bolt and opening of the door.
Generally between the door and the outer post an elastically deformable seal is provided which creates a compression or friction force contributing to the retention of the bolt against a stop.
The term "bolt" is used here in the sense in which it is generally employed in the lock field to refer to the latching member which holds the door closed. In the present invention, this bolt may be a plate angularly displaceable on a housing of the lock mechanism. The housing itself may be any support which can be provided for the lock mechanism and may be a casing, if desired, although it may simply be a mounting plate provided with a notch or slot for the pin.
The stop for the bolt generally is a detent or rest and usually is the main detent of the system which can also be provided with safety detent, i.e. a detent constructed and arranged to prevent undesired opening of the latch. A predetent may also be provided to allow latching of the bolt in a partially closed position or preliminary latching of the bolt.
In practice, a door latching mechanism for motor vehicles of the aforedescribed type exposes the rotary bolt and the pawl, together with the housing, to considerable stress during the closing operation and while the door is held in the closed state. In spite of such stresses, the elements must be capable of withstanding the forces to which they are exposed if the door is to be safely held closed.
The actuating mechanism which must be used in such systems has a large number of levers and other elements for manual operation including handles on the interior and exterior of the door, levers for locking the actuating device, etc. In addition, the actuating mechanism frequently has to overcome the substantial friction forces with which the pawl is held as the closing stop or abutment against the rotary bolt.
All of these considerations have made earlier systems to a greater or lesser extent unreliable.
Power door locking mechanisms for automotive vehicles have also been proposed with an electric motor in the locking-actuating mechanism so that manual operation is not necessary and the door may be opened merely by the operation of a switch or push button controlling the motor.
In these systems, however, rotary bols and pawls of the type previously described cannot be utilized and a different approach to engagement of the pin is used. For example, in such systems the pin can be engaged between the levers of tongs or the like spreadable by the motor when the door is to be opened.
These systems are far less robust than the rotary bolt arrangements and indeed door locks of this type are less secure and in many emergency situations uncontrolled opening of the door may occur.
However, it has not been possible heretofore to simply apply electric motors to rotary bolt locking mechanisms because, when such efforts were made, the high friction forces with which the pawl was held against its abutment on the rotary bolt could not be overcome by motors of reasonable size, and motors dimensioned to overcome such forces could not be accommodated in the door lock structures.